MARPE as an adjunct to orthodontic treatment

ABSTRACT Introduction: Miniscrew or microimplant-assisted rapid palatal expansion (MARPE) devices are used to achieve a skeletal expansion of the palate and to increase the arch perimeter. Objective: To describe the treatment of a 23-year-old woman with an Angle Class II, division 1 malocclusion with constricted maxillary and mandibular arches. Case report: The patient’s main complaint was mandibular anterior crowding. The treatment plan included expansion of the mandibular arch concurrent with maxillary expansion, using a MARPE appliance in combination with a full-fixed appliance to align and level the crowded mandibular teeth, along with miniscrews as anchorage for the maxillary teeth and for distalization of the molars and premolars. A successful non-extraction orthodontic treatment was accomplished after 28 months, and the occlusion and teeth alignment, as well as facial goals, were resolved in a clinically satisfactory manner. Conclusion: The treatment objectives were met, and the outcome of the expansion of the maxillary arch with a MARPE appliance as an adjunct to a fixed appliance was considered a success. An esthetic, functional, and stable result after a 1-year follow-up was achieved and was satisfactory to the patient.


INTRODUCTION
Rapid palatal expansion (RPE) is used to apply lateral forces to the teeth, which increases the perimeter of the arch and disarticulates the midpalatal suture. 1 This can be easily achieved in primary or mixed dentition, by expanding the arch with tooth-borne or tooth-tissue-borne appliances, 2 which relies on a combination of orthopedic and dental expansion to correct the skeletal misalignment. 3 In adult patients, the midpalatal suture presents with increasingly complex interdigitation, which makes it more challenging to split. 4 Thus, surgically-assisted rapid maxillary expansion (SARME) is a procedure commonly performed to correct transverse maxillary deficiencies greater than 5 mm, in patients with complete skeletal maturity and closed cranial sutures. 5 In 2010 6 , RPE reinforced by orthodontic miniscrews (MARPE), positioned on the palatal bone for transverse correction, was introduced; thereby eliminating the need for surgery in patients, and resulted in successful maxillary expansion of the surrounding structures. MARPE emerged as a promising alternative to allow orthopedic expansions without the need for surgical intervention in late adolescence and adulthood. 6 And, to increase the stability of the miniscrews, it was suggested that the anchorage be bicortical instead of the monocortical anchorage. 7 This case report presents the treatment of a 23-year-old female patient, with a Class II, division 1 malocclusion with constricted maxillary and mandibular arches. The clinical outcome of the expanded mandibular arch with archwire associated with MARPE, a full-fixed appliance and miniscrews as anchorage for maxillary teeth distalization was successful, as seen at follow-up one year after treatment.

DIAGNOSIS AND ETIOLOGY
A female patient, aged 23 years and 10 months, sought orthodontic treatment with the main complaint related to esthetic concerns, described as "crowded lower teeth". She was seeking a second opinion and wished to avoid tooth extraction, as well as any form of surgery. Her general state of health was good, with no contributing medical history. Pre-treatment facial photographs ( Fig 1) showed a convex facial profile, with a protruded lower lip.
In the front view, a small asymmetry was visible on the right side, which was a bit rounded compared to the left side.
The pre-treatment intraoral photographs (Fig 1) showed a mild  In the panoramic radiograph, all permanent teeth were visible, including extensive restorations in the second molars and tapered incisor root tips (Figs 2A and 2B).
The analysis of the pretreatment lateral cephalometric radiograph and tracings (Figs 2C and 2D), Table 1  The patient had a constricted maxillary arch, with mandibular molars and premolars that were lingually inclined as a compensatory mechanism. The first objective, therefore, was to expand the maxillary arch transversely to create an adequate skeletal width, in order to correct the position of the teeth. Additional objectives were to achieve correct overbite and overjet, and to improve the dental and skeletal relationships in the three planes of space.

TREATMENT ALTERNATIVES
Options for treatment included the following: 1) Maxillary expansion with a Hyrax-type expander, which would require surgery (i.e., surgically-assisted rapid palatal expansion, SARPE); 2) Maxillary expansion with MARPE, in an attempt to avoid surgery; 3) Maxillary expansion with a Hyrax-type palatal expander fixed to the molars and premolars (a non-surgical procedure); 4) Align, level, and carry out dentoalveolar expansion with the orthodontic archwires and intermaxillary elastics; and 5) Perform light interproximal reduction and extraction of four first premolars.

TREATMENT PROGRESS
The second option was chosen as the treatment plan for this patient.  By the tenth day, the patient reported hearing clicks in the region of the palatal suture and, in the following days, reported the appearance of the midline diastema (Fig 3). There was a discrete opening of the anterior bite due to contact of the buccal cuspid of the left first maxillary molar, which moved in the direction of the overlapping mandibular molar. The activations were stopped after 25 turns and the appliance was stabilized. The radiographic image shows the opening of the midpalatal expansion (Fig 3).
Subsequently, brackets were bonded to all teeth, except for the Miniscrews between the second premolars and first molars were applied to distalize the upper left molars and premolars.

RESULTS
After 28 months of treatment, the esthetic and functional dental and facial goals of the treatment were achieved (Figs 4 and 5).
The patient presented with a convex profile and passive lip sealing.
The Class II malocclusion was corrected, and the overjet and overbite were satisfactorily reduced. For the retention phase, a wraparound type retainer in the maxillary arch was used and worn full-time for one year, after which it would be required for nighttime use only during subsequent years, to maintain occlusal stability. Satisfactory root parallelism was also observed, as can be seen in Figure 5. Clinically significant expansion in both maxillary and mandibular intermolar and intercanine widths was observed (Figs 6 and 7).
The Table 1 shows pretreatment and post-treatment cephalometric measurements. Figure 8 shows the results of the 1-year follow-up, where the stability of the occlusal and transverse expansion can be observed.   Rapid maxillary expansion (RME) is typically the standard treatment method for patients presenting transverse deficiency of the maxillary bone. RME can be successfully carried out in young patients who do not have a closed midpalatal suture, 9 and the treatment can be accomplished with tooth anchorage.
The adult patient in the present case report did not wish to undergo surgery, that is, she did not want to undergo SARPE.
And the RME attempt was not considered due to the uncertainty of the successful outcome. Since MARPE was first described, it has been shown that the maxilla could be expanded with skeletal disjunction and without SARPE. 6 Therefore, the MARPE approach was chosen and executed, and the post-treatment records demonstrate that a successful result was achieved.

The advantages and limitations of non-surgical RPE in adult
patients should be individually analyzed to determine the risks and benefits, 10 as described for the patient reported here.
The selected expander needed to be larger than necessary for the expansion, along with bicortical anchorage (oral and nasal) for achieving the successful outcome described in our case report. The expander selected needs to deliver the maximum expansion capacity and should be kept at an ideal vertical distance from the palatal mucosa, as was achieved in the present case report. If the expander is too distant from the mucosa (more than 2 mm), the miniscrew may fail to reach the nasal cortical bone, as reported by Brunetto et al. 11 Ricketts et al. 12 concluded that 1 mm of canine expansion produces 1 mm of arch length increase, and 1 mm of molar expansion results in an increase of 0.25 mm in arch length.
Thus, to achieve a good outcome for the non-extraction treatment used in the present case, with a crowded and constricted dental arch, it was necessary to increase the arch perimeter to allow for arch alignment and leveling.
The present case report showed that maxillary and mandibular arch expansion, followed by a fixed orthodontic appliance, led to increases from 23 mm to 28 mm in intercanine width, and 41 mm to 49 mm in intermolar width for the lower arch.
In the upper arch, intercanine distance increased from 32 mm to 35 mm, and intermolar distance from 47 mm to 56 mm.
The arch perimeter increased 5.3 mm and 6.0 mm for mandibular and maxillary arches, respectively. Adkins et al. 13  We observed a clinically favorable occlusion and esthetic gain in our patient 1 year after treatment. Permanent mandibular retention was chosen due to the strong tendency toward arch-width relapse, as described in the literature. 15 In addition, mandibular crowding was the patient's main complaint before treatment.
The present patient showed an improvement in the gingival leveling of the mandibular incisors, resulting from orthodontic alignment and protrusion, and no gingival recession was detected over the long term. Gingival recession associated with orthodontic treatment is a controversial issue, but no association between proclined teeth and gingival recession was found after a 5-year follow-up. 16 Gingival recession may also be influenced by gingival phenotype, but the present patient had a gingival phenotype that could be classified as optimal.
Overall, simultaneous maxillary and mandibular arch expansion using a nonsurgical approach is a viable procedure for young adults. In selected cases, it can offer a clinically favorable result in the long term. No periodontal disease occurred in this patient, since she presented good oral hygiene. The authors report no commercial, proprietary or financial interest in the products or companies described in this article.